Fuel is sucked from a fuel tank by a fuel pump through a filter device, and a portion of the sucked fuel, which is returned after pressure-regulation, is normally carried back into the fuel tank and is mixed with an unfiltered portion of the fuel remaining in the fuel tank. Since such a returned portion of the fuel has been already filtered by the filter device, it is unreasonable that the returned portion of the fuel is mixed with such an unfiltered portion of the fuel. From this point of view, there has been proposed a system wherein a fuel pump and a path for a returned portion of the fuel are connected at different positions to an upper portion of a filter device in a fuel tank (see Patent Document 1). However, this system simply carries back the returned portion of the fuel into the filter device since the path for the returned portion of the fuel is merely connected to the upper portion of the filter device. It is supposed that a flow of the returned portion of the fuel has an adverse effect on operation for sucking the fuel in this system since the path for the returned portion of the fuel is connected to the filter device at a position lateral to a path extending to the fuel pump and connected to the upper portion of the filter device.
Patent document 1: JP-9-4537